Credit Card Theft
Stolen credit/debit card numbers are sold for mere dollars on the black market. This is because they are so ubiquitous as they are lost in data breaches all the time.
Privacy.com
Privacy.com allows the creation of virtual visa/mastercard gift cards that function like a debit card. This service is free as Privacy.com takes a portion of the fee that is payed to the card company (Visa or Mastercard) by the merchant. There is also a paid option with added benefits.
For one-off purchases, there are one-time use cards that close after they have been used. Meaning that even if the number is stolen it can’t be used again. There are also multi-use cards with finely customizable spending and transactions limits. Also, each of these cards can only be used for one merchant. So if a card is used at merchant A, it can’t then be used for merchant B, as it is already locked to merchant A. This helps minimize the damage a stolen card number may cause, as it would have to be used at the same place. Cards can also be closed or paused at any time.
Privacy.com is a privacy and security focused company with a great track record and a good privacy policy that limits sharing of personal data.
Bank Accounts
A similar topic is securing your bank account access. It should have a completely unique password, different from any other website. Enable multifactor authentication if it is supported. For security questions (eg: what is your mothers maiden name?), do not enter the true information as this can be trivially guessed, found online, or learned through social engineering. Instead, use random answers (eg: What is your home town? “New York”) and save it in a password manager. Security questions are easily guessed or figured out by attackers, so they should not be the “true” answer. While this may seem like an odd thing to do, it is increasingly recommended to protect accounts.